Suppression of CMAS penetration by synergistic modulation of reaction-phase barrier in multi-rare-earth co-doped zirconia

Molten calcium-magnesium-alumino-silicates (CMAS) corrosion poses a critical challenge to the corrosion resistance of thermal barrier coatings (TBCs) in advanced turbine engines. In this work, a novel material design strategy is developed to enhance CMAS corrosion resistance by controlling the reaction-precipitated phase composition and structure through multi-component rare earth (Y/Gd/Yb) optimization. Through cationic synergy optimization, a defect-fluorite ceramic Zr_3/7Y_8/21Yb_2/21Gd_2/21O_12/7 (YYbGdZO) was synthesized, demonstrating fundamentally distinct CMAS penetration resistance compared to conventional gadolinium zirconate (GZO). It was found that the CMAS penetration depth of YYbGdZO was reduced by 98 % compared to GZO after 100 h of exposure at 1400 °C. This improvement is attributed to the synergy of multi-rare earth elements in YYbGdZO, which selectively reacts with components in molten CMAS, forming a protective (Y,Yb,Gd)₂Si₂O₇-apatite/rare-earth-stabilized zirconia composite barrier that significantly enhances the material's resistance to CMAS and long-term stability. This study provides a novel strategy for the optimization of materials resistant to molten sand erosion under extreme high-temperature environments.